Income Taxes, Valuation allowance and tax carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income taxes
Valuation allowance, related to the foreign net operating loss carryforwards and U.S. state tax credits	$ 46.6	$ 42.2
Change in the valuation allowance, related to foreign net operating loss and foreign and U.S. state credit carryforwards	4.4	$ (2.7)
Foreign
Income taxes
Loss carryforwards	177.3
Operating loss carryforwards to expire or be refunded	5.2
U.S. Federal
Income taxes
Loss carryforwards	9.1
Operating loss carryforwards to expire or be refunded	9.1
Tax credit carryforwards	2.3
Tax credit carryforwards to expire or be refunded	2.3
U.S. State
Income taxes
Loss carryforwards	101.7
Operating loss carryforwards to expire or be refunded	101.7
Tax credit carryforwards	17.6
Tax credit carryforwards to expire or be refunded	$ 11.7